Welcome everyone. As you may know i have up in the general section about changing my belt tensioner, belt and idler pulley. I completed this job successfully and will do the best i can to write my first DIY to replace the tensioner, serpentine belt and idler pulley...

i don't remember seeing a cap. I'm going to have to see my old one and report back.

Just finished switching out the tensioner, idler pulley, and belt. You are correct, there is no cap covering the install bolt on the tensioner. The cap I ordered actually covers the wheel of the tensioner, which already comes with a cap when purchased new. Oh well, it was only a couple bucks so no biggie.

i don't remember seeing a cap. I'm going to have to see my old one and report back.

Just finished switching out the tensioner, idler pulley, and belt. You are correct, there is no cap covering the install bolt on the tensioner. The cap I ordered actually covers the wheel of the tensioner, which already comes with a cap when purchased new. Oh well, it was only a couple bucks so no biggie.

Does anyone know what the tightening torque specs are for the tensioner and idler pulley? The aluminum tensioner bolt (new) should have a specified torque value. The only thing I could find was a BMW TIS document that suggested a tightening torque of 11 28 1AZ...whatever that means!

I guess I'm really surprised that this info is not available in the Bentley manual...

I'm trying to do this right now and I've got it bolted back up to the block however when trying to unload the tensioner further, the T60 is turning instead of unloading the tensioner? I've probably turned it now maybe 2 full turns but I need to get it to turn just a bit so I can pull the pin out??

Yeah I'm a damn fool. hahaha. So to unload it when i took the old one off, I put a T50 torx on the pulley itself. That worked great. When I was putting it back on, I tried to do the same thing and obviously that failed. So I went out, got myself a T60 and used the designated slot for that and it worked like a charm. Thanks for the follow up and to the OP for the write up!

I'm about to try to replace my tensioner. I order the tensioner, bolt and belt. When I looked at it yesterday, it looks like the head of the bolt is sheared off. The tensioner puller may be okay but the entire part may have moved since the head of the bolt is gone. If so, I may just replace it anyway since I ordered it. FINGERS CROSSED

loweran and E90MYKE I saw that both of you had the same issue I had with the head of the bolt coming off. I checked the pulley on my e90 and its not loose as shown in the videos in recent posts. I also checked the other pulleys and they seem fine as well. My question is, can you get away with just replaceing the bolt or do you have to replace the tensioner assembly as well? I can "wiggle" the tensioner some what but it doesn't have alot of play in it.

I drive a 2007 320i (4-syl) with 56.000 miles on it, and I have a rattling noise coming from the front area of the engine when I rev it past 1400 rpm. If I also drive with low gearing and my engine pulls 'heavy' past 1400 rpm, it also gives away a rattling noise.

was wondering what can happen if i have a "crooked belt tensioner"? i have a '06 330i, and the car runs great. Starts up without problems everytime, no strange noises, runs perfectly. But I took it for an inspection recently (independent BMW mechanic) and was told that I have a "crooked belt tensioner". What types of symptoms, if any, should i expect to see from this? What can happen if I do not get this fixed asap? How can i check and verify this myself?

was wondering what can happen if i have a "crooked belt tensioner"? But I took it for an inspection recently (independent BMW mechanic) and was told that I have a "crooked belt tensioner". What types of symptoms, if any, should i expect to see from this? What can happen if I do not get this fixed asap? How can i check and verify this myself?

Thank you

It would cause increased belt wear and pre-mature belt failure -- that could leave you stranded somewhere, and could, outside chance, damage the A/C compressor.

Check that the belt is running in a flat plane between all the pulleys, and the tensioner is not forward or back. Look for wear on the edge of the belt. A couple of people have reported broken mounting bolt on the tensioner, look for that. See the above thread for details and photos.

was wondering what can happen if i have a "crooked belt tensioner"? i have a '06 330i, and the car runs great. Starts up without problems everytime, no strange noises, runs perfectly. But I took it for an inspection recently (independent BMW mechanic) and was told that I have a "crooked belt tensioner". What types of symptoms, if any, should i expect to see from this? What can happen if I do not get this fixed asap? How can i check and verify this myself?

Thank you

I have the same problem. My belt is off centered by at least 3mm. I'll by changing the tensioner, belt and idle pulley this weekend. I'll let you know if it fixed the problem

Guys, I am buying the torx tools, can you please advise what type of torx bolt it is. Someone stated e16. Did they mean t16?

Thanks for the write up and all the great comments

It would be an "E" Torx socket. "E" means the bolt head is an external Torx i.e. the bolt head looks like a Torx bit. I don't think the bolt head is big as an E16 though; I think it is an E12. Just get a standard set of Torx sockets and the correct size should be in the set.

What if you have just a idler pulley that free spins? Meaning if you rotate it, it spins without any resistance? It doesn't make that sand grainy sound. Is it still bad?

It means that the bearings aren't bad (making the sand grainy sound), but that the lubrication is not would it should be (spinning freeing), and it's only a matter of time, perhaps short, before the bearings will be shot.

I was in the same boat with mine, at 80K mls, and decided to replace them both with the belt. The chances are I won't have this car at 160K, when they'll need to be replaced again, so why risk them breaking the belt and leaving me stranded, and possible damage to my A/C compressor, which is on a lot in Phoenix (so more risk.)